Since all of the passengers for upper floors of a building must travel upwardly through the lower floors of the building, very tall buildings require effective use of elevator hoistways in order to conserve space used for elevators (referred to herein as the "core" of the building). In a commonly owned U.S. patent application Ser. No. 08/564,703, filed on Nov. 29, 1995, an elevator shuttle includes overlapping elevator hoistways, each having a double deck car frame therein. A cab traveling in one direction (up, down) is transferred from the lower deck of one elevator car frame to the lower deck of the other car frame, simultaneously with transferring a cab traveling in the opposite direction (down, up) from the upper deck of the other car frame to the upper deck of the one car frame.
A commonly owned U.S. patent application Ser. No. 08/588,577 filed on Jan. 18, 1996 discloses an elevator shuttle system employing extra deck car frames that can provide elevator service in a similar manner between a pair of landings, utilizing three or more hoistways.
In both of the aforementioned shuttles, service is provided only between a first level of a building and a second level which is vertically remote from the first level. A commonly owned U.S. patent application Ser. No. 08/564,534, filed on Nov. 29, 1995, discloses a synchronous elevator that provides service to three floors using two elevator hoistways, with each elevator cab traversing a fixed route from one landing at a first level to a second landing at a second level and so forth until it reaches a second landing at the first level, after which it proceeds to other landings at other levels until it returns to the first landing at the first level. However, that system provides a balanced transfer between each of the three levels and each other of the three levels. In that system, much of the capacity of the system is utilized for traffic between the intermediate level and both the lower level and the upper level, in addition to travel from the lowest level to the highest level.